Pavement.



PATENTED MAY 5, 1903. F. J. WARREN.

PAVEMENT.

APPLIUATION FILED MAY 1s, 1901.

A1m MODEL.

/A Wt phalt roadways is with the use of Patented May 5, 1903.

'PATENT OFFICE.

FREDERICK JOHN WARREN, OF NEWTON, MASSACHUSETTS.

PAVEMENT.

srncnca'rron arming part of Letters Patent No. 727,508, dated May 5, '1903. Application iled May 18| 1901. Serial No. 60,819. (No specimens.)

To blt wir/0711, t may concern.-

Be it known that I, FREDERICK JOHN VAR- REN, a citizen ofthe United States, residing at Newton, in the county of Middlesex and State of Massachusetts, have invented a new and useful Improvement in Pavements, of which the following is a full, clear, and exact description.

The invention relates to an improvement in the class of pavements consisting of a base of mineral grains of various sizes united by a cementing medium of asphalt cement or composition, Which constituents are thoroughly incorporated together and form the upper wearing-surface of the pavement.

'lhe invention is based on the discovery that the cementing medium, which is composed of a relatively hard asphalt softened with a softer asphalt or oil flux or a relatively soft lnatural asphalt without the addition of uX,

is subject to deterioration by the oxidation, volatilization, or disintegration of the softening oils or asphalt, and when this takes, place thecementing medium, being robbed of its softening elements, becomes hard and brittle, causing the pavement to flake, crack, and chip, lessening its life and usefulness.

The ordinary method of constructing asfine sand admixed with an asphalt cement of the consistency produced by the use of from sixteen to twentypounds of petroleum residuum of 20 gravityBauxn with one hundred pounds of Trinidad Lake rened asphalt, and the larger portion of the best pavements have beenlaid with an asphalt cement of the consistency whichv would be produced by the use of eighteen pounds of petroleum residuum. A pavement constructed with the cement as a binding medium would become hard, brittle, and lifeless in c old Weather on losing onesixth of its softening-oil from the action of the sun and the elements orfrom other causes.

I have discovered that by the proper selection of the mineral portion of the pavement a muchsofter asphaltic cement can be used, relying principally on the rigidity of the mineral aggregatesto prevent the displacement of the surface bytraffic. that if an asphaltic vcement can be used softer than that produced by the use of-twenty-two pounds of petroleum rcsiduum with one hun- It will then be scendred pounds Trinidad Lake 4refined asphalt the amount of iiuxing-oil which can be lost and still maintain the cementing medium plastic is greatly increased, and hence the life and usefulness of the pavement are largely enhanced.

I prefer to use in connection with bituminous macadam roadways an asphalt cement of such consistency as would be produced by the addition of from twenty-two to thirty-ve pounds of petroleum residuum, varying the consistency with the rigidity of the mineral aggregate when. rolled; but under favorable conditions even softer cementv may be used with equally good effect.

Any combination of mineral elements which shall produce stability may be used, and I do not limit myself to any especial proportion of sizes for producing this resul In the drawings I have shown conventional y representations of a pavement having the features of my invention.

Figure I is a view in cross vertical section of such a pavement, and Fig. 2 is an enlarged View of the same.

Before the invention of the type of streetpavements to which my present invention belongs the use of a relatively soft bituminous composition in streetpavements was unknown. This arose from the fact that it was necessary to use a bituminous composition that would be hard enough when laid to maintain the lmineral ingredients in position. I have discovered notl only that it is desirable to use mineral ingredients which from their size and proportions will thus provide a stability which does not rely principally upon the bituminous composition, but I have also discovered that because this duty is taken from the bituminous composition and transferred to the mineral base a softer bituminous composition may be employed in the pavement, as its principal use is now to fill the interstices and act as a waterprooti ng medium and as areinforce.

I prefer a bituminous composition having the degree of softness which I have above described. 'lhe use of such a bituminous composition very much improves the pavement,in that it increases its life very remarkably. It provides a cushioning or elasticity for it which helps traffic. It is constantly self-repairing under use. It stands strains of variations of temperature without cracking or disintegrating. lt deadens sound and prevents the formation of dust, and last, but not least, it also can be laid much more cheaply, because it is possible to lay it at temperatures of 150 or less rather than at 3000, as is requisite with the old'form of asphalt pavemen Having thus fully described my invention, I claim and desire to secure by Letters Patent of the United States- 1. A Wearing-section of a street-pavement consisting of a mineral base composed of mineral elements selected and combined to 20 gravity Baume in one hundred parts of Trinidad Lake asphalt.

3. A pavement composed of mineral or wearing ingredients having an inherent stability and a cement of a permanentconsistency softer than twentytwo parts of petroleum residuum of 20 gravity Baume in one hundred parts of Trinidad Lake asphalt.

4. A pavement composed of mineral or Wearing ingredients so graded and admixed as to have an inherent stability and a cement of a consistency softer than twenty-two parts of petroleum residuum of 20 gravity Baume in 011e hundred parts of Trinidad asphalt.

15 provide the base Withinherent stability, and 5. A pavement of mineral or Wearing ina bituminous uniting and combining medium gredients having an inherent stability and a comprising a bituminous composition having cement of a permanent softness equal to that the degree of softness herein indicated and resulting from treating one hundred parts of adapted to ll the interstices and provide a Trinidad Lake asphalt with from twenty-two 2o lexible,waterproof, coherent, cushioning meto thirty-five parts of petroleum residuum of digm f 1 20o gravity Baume.

2. mixture o minera or Wearing ingre- 1 dients so graded and mixed as to havre an in- FREDERKJK JOHN WARREN' herent stability in combination with an aslitnesses:

25 phalt cement of a consistency softer than F. F. RAYMOND, 2d,

twenty-two parts of petroleum residuum of J. M. DOLAN.

fa/j, a aaa. /fff dw., /f fr www, 57d: am. 4x'

f Vf Mfr/716? 7a4- #7a/Mayu 

